It's an interesting country to be sure. And it's odd you ask this since I'm writing this from a cafe in Auckland.
My gut feeling is that a significant part of the economy is heavily influenced by government policy, but the most important one has a decent level of autonomy. I speak, of course, of food production.
In a sense, the relative freedom of this country, I think, is due to the relative peace they've had over the years. No one is trying to invade it, for example.